problems again

Some time ago, I tried to do a scan disc(or check disc as it is in xp).Normally when you do that, you can either leave the 2 boxes unchecked or check them. I checked them, as I always have done and then it schedules a scan disc for when windows next boots up. Only for ages now it wont do it. When I start up windows I get the blue screen that says,
“cannot open volume for direct access. windows has finished checking the disc”
I tried to do it yesterday leaving the boxes unchecked and it did the first 2 phases but then said “windows is unable to complete scan disc” or words to that effect. I,ve run a virus scan, defgrag and spyware. No virus and any nasty spyware removed. Also when I boot up I get the little windows update icon appear in my taskbar. When I click on it, it doesnt update anything and then after a couple of minutes it vanishes. I also frequently get screen freezes, which is why I did the virus scan, and have to reboot.( I dont know how else to get out of a screen freeze other than re-booting). Because of all this crap it takes ages and ages to boot up now. So, Mr Owen google Cash, what do you reckon then?
I dont really want to spend a fortune on my pc repair man(45 quid an hour!!!) or bother poor PB again.(he must get sick of the sound of my voice on the phone) help!! poor Bat.